Quantum Dot electroluminescent devices have the advantages of high color gamut, bright color, sharp contrast, and being suitable for fabricating large size devices, and are therefore developed by companies and research institutions widely. In particular, quantum dot electroluminescent devices formed through solution process attracts wide attention recently for a large potential in industrial application.
Typical structure of existing quantum dot electroluminescent device comprises an anode, a hole injection transport layer, a quantum dot light emitting layer, an electron injection transport layer and a cathode provided sequentially, wherein the hole injection transport layer, the quantum dot light emitting layer, and the electron injection transport layer form a light emitting layer. In practical applications, the electron injection transport layer may be configured as two layers including an electron transport layer and an electron injection layer, and the hole injection transport layer may also be configured as two layer including a hole transport layer and a hole injection layer.
An optimal material for ETL (electron transport layer) in the quantum dot electroluminescent device is ZnO (Zinc Oxide) nanoparticle, and an optimal material for HTL (hole transport layer) is TFB, poly (9,9-two octyl fluorene-co-N-(4-butyl phenyl) two aniline)). In solution process of the quantum dot electroluminescent device with largest potential in industrial application, solvent such as toluene, chloroform and so on containing the quantum dot materials is generally subjected to a deposition process to form a film layer; other film layers may also be obtained by solution deposition or spin coating followed by thermal evaporation. However, the solvent for current spin coating may cause damage to existing film layers, e.g. the deposited TFB will be dissolved by the quantum dot solvent (toluene), causing HTL damage, thereby the hole transport layer cannot reach a desired structure size, resulting in performance degradation of light emitting devices.